I'm wondering where this "private land" is that mumsnetters keep referring to? There are so many references that I'm assuming there is more of it than on livery yards. And why can't dog owners find some of it as well to let their dogs off the lead on?
I'm also wondering where you can find these bombproof horses which can be guaranteed never to react to anything that would give the average horse a fright. Maybe a mechanical horse?
Mine is bombproof, but if a dog chased him and snapped at his heels or bit him, I'm pretty sure he would either kick out or bolt. More likely he'd spook a little and get bitten badly because he did neither of the two above dramatically enough.
I think its time to discuss banning dogs being off the lead in public places which are not designated for the purpose. Its not just horseriders that get injured by them.
Or at least have them go through an annual test to get a license for being off the lead in public places, so that the owner's training, particularly obedience to recall, is tested. I get the impression that some dog owners are so ineffective, they either never bother to train their dogs at all or are pretty useless at it. I spent half an hour recently avoiding, stopping and shouting at an out of control dog that followed me and my horse, trying to lead it back to the owner, only for her to let it go again the moment she could no longer see us and for it to immediately return to start circling us, growling, teeth bared, sliding across the grass on its belly to get closer, then running quickly behind my horse's heels and snapping at them. Every time we tried to ride away it would circle in front again. It was actually another dog owner that grabbed hold of it in the end so we could get away. And that's not the only incident that's happened.
When you come across one of these out of control, off the lead dogs, its a nightmare. You have to stop whatever you're doing while a dog stalks you, while the owner has been left behind out of sight. I used to think they would never bite until I was bitten, and now I know they can. I have a local dog club near me where the owners have great fun doing obstacle courses with their dogs. Those dogs are well trained. I ride past it all the time and not once have I been chased by an out of control dog. They have to hire private land to do it on of course, but it is possible.
I also have third party insurance for my horse, as does just about every horse owner I know that competes with their horse and therefore regularly takes it off the yard. Do dog owners tend to have third party insurance? Plus I am required by law to have a passport for my horse, which identifies me as its owner, and produce it when required to prove it. Its idiocy not to have similar for dogs, when there is a case almost every week of someone (usually a child) being badly bitten by a dog.